Liquid Crystal Display Device

ABSTRACT

A liquid crystal display device includes an array substrate including a pixel electrode which is disposed in each of pixels, a counter-substrate which is disposed to be opposed to the array substrate and includes a counter-electrode which is common to a plurality of the pixels, and a liquid crystal layer which is held between the array substrate and the counter-substrate. The pixel electrode includes a first major electrode portion having a strip shape, and the counter-electrode includes second major electrode portions each having a strip shape, the second major electrode portions being disposed in parallel to the first major electrode portion in a manner that the first major electrode portion is interposed between the second major electrode portions and that the first major electrode portion and the second major electrode portions are alternately arranged.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority fromprior Japanese Patent Application No. 2008-033437, filed Feb. 14, 2008,the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a liquid crystal displaydevice, and more particularly to a liquid crystal display device whichincludes a pixel electrode on an array substrate, includes acounter-electrode on a counter-substrate, and generates a transverseelectric field between the pixel electrode and the counter-electrode.

2. Description of the Related Art

In recent years, flat-panel display devices have vigorously beendeveloped, and liquid crystal display devices attract particularattention by virtue of their advantages of light weight, small thicknessand low power consumption. In particular, in an active matrix liquidcrystal display device in which a switching element is provided in eachof pixels, attention has been paid to the structure which makes use of atransverse electric field (including a fringe electric field), such asan IPS (In-Plane Switching) mode or an FFS (Fringe Field Switching) mode(see, for instance, Jpn. Pat. Appln. KOKAI Publication No. 2005-3802).

The liquid crystal display device of the IPS mode or FFS mode includes apixel electrode and a counter-electrode, which are formed on an arraysubstrate, and liquid crystal molecules are switched by a transverseelectric field that is substantially parallel to the major surface ofthe array substrate. In addition, polarizer plates, which are disposedsuch that their axes of polarization intersect at right angles, aredisposed on the outer surfaces of the array substrate and thecounter-substrate. By this disposition of the polarizer plates, forinstance, at a time of non-application of a voltage, a black screen isdisplayed, and with the application of a voltage corresponding to avideo signal to the pixel electrode, the light transmittance (modulationratio) gradually increases and a white screen is displayed. In thisliquid crystal display device, the liquid crystal molecules rotate in aplane that is substantially parallel to the major surface of thesubstrate. Thus, since the polarization state is not greatly affected bythe direction of incidence of transmissive light, there is the featurethat the viewing angle dependency is low and a wide viewing anglecharacteristic is obtained.

A transverse-electric-field-mode liquid crystal display device having apixel electrode and a counter-electrode on one of the substrates cannotbe fabricated by using a conventional process of avertical-electric-filed mode liquid crystal display device, such as a TN(Twisted Nematic) mode liquid crystal display device, which has a pixelelectrode and a counter-electrode on different substrates. Thus,different manufacturing lines are needed, or the manufacturing lineneeds to be reassembled. This may cause an increase in manufacturingcost.

Furthermore, in the transverse-electric-field-mode liquid crystaldisplay device, it is difficult to form an electric field, which isparallel to the major surface of the substrate, over the pixelelectrode. Thus, compared to the vertical-electric-filed mode liquidcrystal display device, the transmittance is lower.

BRIEF SUMMARY OF THE INVENTION

The present invention has been made in consideration of theabove-described problems, and the object of the invention is to providea liquid crystal display device which suppresses the manufacturing cost,has wide viewing angle characteristics, improves the transmittance, andhas good display quality.

According to an aspect of the invention, there is provided a liquidcrystal display device comprising: an array substrate including a pixelelectrode which is disposed in each of pixels; a counter-substrate whichis disposed to be opposed to the array substrate and includes acounter-electrode which is common to a plurality of the pixels; and aliquid crystal layer which is held between the array substrate and thecounter-substrate, wherein the pixel electrode includes a first majorelectrode portion having a strip shape, and the counter-electrodeincludes second major electrode portions each having a strip shape, thesecond major electrode portions being disposed in parallel to the firstmajor electrode portion in a manner that the first major electrodeportion is interposed between the second major electrode portions andthat the first major electrode portion and the second major electrodeportions are alternately arranged.

The present invention can provide a liquid crystal display device whichsuppresses the manufacturing cost, has wide viewing anglecharacteristics, improves the transmittance, and has good displayquality.

Additional objects and advantages of the invention will be set forth inthe description which follows, and in part will be obvious from thedescription, or may be learned by practice of the invention. The objectsand advantages of the invention may be realized and obtained by means ofthe instrumentalities and combinations particularly pointed outhereinafter.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate presently preferred embodiments ofthe invention, and together with the general description given above andthe detailed description of the preferred embodiments given below, serveto explain the principles of the invention.

FIG. 1 schematically shows the structure of a liquid crystal displaydevice according to an embodiment of the present invention, which is ofa liquid crystal mode making use of a transverse electric field;

FIG. 2 is a cross-sectional view that schematically shows the structuresof an array substrate and a counter-substrate, which are applied to theliquid crystal display device shown in FIG. 1;

FIG. 3 is a plan view that schematically shows the structure of onepixel of the liquid crystal display device according to the embodiment;

FIG. 4 is a cross-sectional view of a liquid crystal display panel,taken along line IV-IV in FIG. 3;

FIG. 5 is a plan view that schematically shows the structure of onepixel of a liquid crystal display device according to a firstcomparative example;

FIG. 6 shows a simulation result of an alignment direction of liquidcrystal molecules at a time of voltage application in the embodiment;

FIG. 7 shows a simulation result of an alignment direction of liquidcrystal molecules at a time of voltage application in the firstcomparative example;

FIG. 8 is a plan view that schematically shows the structure of onepixel of a liquid crystal display device according to a modification ofthe embodiment;

FIG. 9 shows a simulation result of the relationship between anequipotential surface and an alignment direction of liquid crystalmolecules at a time of voltage application in the embodiment;

FIG. 10 shows a simulation result of the relationship between anequipotential surface and an alignment direction of liquid crystalmolecules at a time of voltage application in the modification;

FIG. 11 is a plan view that schematically shows the structure of onepixel of a liquid crystal display device according to a secondcomparative example;

FIG. 12 shows a verification result of the effect that is obtained bydisposing a pixel electrode and a counter-electrode on differentsubstrates in a transverse electric field mode; and

FIG. 13 is a plan view that schematically shows the structure of onepixel of a liquid crystal display device which includes two first majorelectrode portions.

DETAILED DESCRIPTION OF THE INVENTION

A liquid crystal display device according to an embodiment of thepresent invention will now be described with reference to theaccompanying drawings. In the description below, exemplification is madeof a liquid crystal mode in which an array substrate includes a pixelelectrode, a counter-substrate includes a counter-electrode, and liquidcrystal molecules are switched by mainly using a transverse electricfield which is formed between the pixel electrode and thecounter-electrode (i.e. an electric field which is substantiallyparallel to the major surface of the array substrate).

As shown in FIG. 1, FIG. 2 and FIG. 3, the liquid crystal display deviceis an active matrix liquid crystal display device, and includes a liquidcrystal display panel LPN. The liquid crystal display panel LPN includesa pair of substrates, namely, an array substrate AR and acounter-substrate CT which is disposed to be opposed to the arraysubstrate AR.

Further, the liquid crystal display panel LPN includes a liquid crystallayer LQ which is held between the array substrate AR and thecounter-substrate CT. This liquid crystal display device includes adisplay area DSP which displays an image. The display area DSP iscomposed of a plurality of pixels PX which are arrayed in a matrix ofm×n.

The array substrate AR is formed by using an insulating substrate 10with light transmissivity, such as a glass plate or a quartz plate.Specifically, the array substrate AR includes, in the display area DSP,an (m×n) number of pixel electrodes EP which are disposed in associationwith the respective color pixels PX; an n-number of scanning lines Y (Y1to Yn) which extend in a row direction of the pixels PX; an m-number ofsignal lines X (X1 to Xm) which extend in a column direction of thepixels PX; an (m×n) number of switching elements W which are disposed inregions including intersections between the scanning lines Y and signallines X in the respective pixels PX; and storage capacitance lines AYwhich are disposed in a manner to extend in the row direction, like thescanning lines Y, and are capacitive-coupled to the pixel electrodes EPso as to constitute storage capacitances CS in parallel with liquidcrystal capacitances CLC.

The array substrate AR further includes, in a driving circuit region DCTaround the display area DSP, at least a part of a scanning line driverYD which is connected to the n-number of scanning lines Y, and at leasta part of a signal line driver XD which is connected to the m-number ofsignal lines X. The scanning line driver YD successively supplies ascanning signal (driving signal) to the n-number of scanning lines Y,based on the control by a controller CNT. The signal line driver XDsupplies video signals (driving signals) to them-number of signal linesX, based on the control by the controller CNT at a timing when theswitching elements W of each row are turned on by the scanning signal.Thereby, the pixel electrodes EP of each row are set at pixel potentialscorresponding to the video signals that are supplied via the associatedswitching elements W.

Each of the switching elements W is composed of, e.g. a thin-filmtransistor. A semiconductor layer 12 of the switching element W can beformed of, e.g. polysilicon or amorphous silicon. The semiconductorlayer 12 includes a source region 12S and a drain region 12D, betweenwhich a channel region 12C is interposed. The semiconductor layer 12 iscovered with a gate insulation film 14.

A gate electrode WG of the switching element W is connected to oneassociated scanning line Y (or formed integral with the scanning lineY), and is disposed, together with the scanning line Y and storagecapacitance line AY, on the gate insulation film 14. The gate electrodeWG, scanning line Y and storage capacitance line AY are covered with aninterlayer insulation film 16.

A source electrode WS and a drain electrode WD of the switching elementW are disposed on the interlayer insulation film 16 on both sides of thegate electrode WG. The source electrode WS is connected to oneassociated signal line X (or formed integral with the signal line X) andis put in contact with the source region 12S of the semiconductor layer12. The drain electrode WD is connected to one associated pixelelectrode EP (or formed integral with the pixel electrode EP) and is putin contact with the drain region 12D of the semiconductor layer 12. Thesource electrode WS, drain electrode WD and signal line X are coveredwith an organic insulation film 18.

The pixel electrode EP is disposed on the organic insulation film 18 andis electrically connected to the drain electrode WD via a contact holewhich is formed in the organic insulation film 18. As shown in FIG. 3,the pixel electrode EP includes a first major electrode portion EPa anda first sub-electrode portion EPb. The first major electrode portion EPahas a strip shape, and is disposed linearly in parallel to the columndirection. In this example, one first major electrode portion EPa isprovided in each pixel PX, and is disposed at a central part of thepixel PX, that is, at a substantially equidistant position from theneighboring signal lines X. The first sub-electrode portion EPb isdisposed to be opposed to the storage capacitance line AY.

The first major electrode portion EPa and first sub-electrode portionEPb, which constitute the pixel electrode EP, can be integrally formedof the same material, and, for example, can be formed of alight-transmissive, electrically conductive material, such as indium tinoxide (ITO) or indium zinc oxide (IZO). By forming the first majorelectrode portion EPa of the light-transmissive, electrically conductivematerial, light can pass through the first major electrode portion EPaand the transmittance can be improved.

The pixel electrodes EP of all pixels PX are covered with a firstalignment film 20.

The scanning line Y and storage capacitance line AY are disposedsubstantially parallel, and can be formed of the same material. Thestorage capacitance line AY is disposed to be opposed to the pixelelectrode EP via an insulation film such as the interlayer insulationfilm 16, and to cross the plural pixel electrodes EP. The signal line Xis disposed to intersect substantially at right angles with the scanningline Y and storage capacitance line AY via the interlayer insulationfilm 16. The signal line X, scanning line Y and storage capacitance lineAY are formed of an electrically conductive material, such as aluminum,molybdenum, tungsten, or titanium.

On the other hand, the counter-substrate CT is formed by using alight-transmissive insulating substrate 30 such as a glass plate or aquartz plate. Specifically, the counter-substrate CT includes acounter-electrode ET in the display region DSP, which is common to theplural pixels PX. The counter-electrode ET is electrically connected toa common wiring line COM to which a common potential is supplied,outside the display region DSP.

As shown in FIG. 3, the counter-electrode ET includes second majorelectrode portions ETa. The second major electrode portions ETa havestrip shapes and are disposed linearly in parallel to the columndirection over the entire display area DSP. In this example, neighboringsecond major electrode portions ETa sandwich one first major electrodeportion EPa, and are disposed at a substantially equidistant positionfrom the first major electrode portion EPa.

In addition, in the example shown in FIG. 3, the second major electrodeportions ETa are disposed to be opposed to the signal lines X.

As shown in FIG. 4, the second major electrode portions ETa and thefirst major electrode portion EPa are alternately disposed in parallelso that a transverse electric field is formed between each of the secondmajor electrode portions ETa and the first major electrode portion EPa.Specifically, the second major electrode portion ETa is disposed so asnot to be opposed to the first major electrode portion EPa. The firstmajor electrode portions EPa and second major electrode portions ETahave a combtooth pattern. FIG. 4 depicts only a main part that isnecessary for the description.

The second major electrode portions ETa, which constitute thecounter-electrode ET, can be formed of a light-transmissive,electrically conductive material such as ITO. By forming the secondmajor electrode portion ETa of the light-transmissive, electricallyconductive material, light can pass through the second major electrodeportion ETa and the transmittance can be improved.

The counter-electrode ET is covered with a second alignment film 36.

The liquid crystal display device of a color display type includes acolor filter layer 34 which is provided on the inner surface of theliquid crystal display panel LPN in association with each pixel PX. Inthe example shown in FIG. 2, the color filter layer 34 is provided onthe counter-substrate CT. The color filter layer 34 is formed of colorresins of a plurality of different colors, for example, the threeprimary colors of red, blue and green. The red color resin, blue colorresin and green color resin are disposed in association with a redpixel, a blue pixel and a green pixel, respectively.

In the example of the color-display-type liquid crystal display deviceas shown in FIG. 2, the color filter layer 34 is disposed on thecounter-substrate CT side. However, the color filter layer 34 may bedisposed on the array substrate AR side.

The respective pixels PX are partitioned by a black matrix 32. The blackmatrix 32 is formed of, e.g. a black color resin, and is disposed to beopposed to the scanning lines Y, signal lines X and wiring portions ofthe switching elements W, etc., which are provided on the arraysubstrate AR. In the color-display-type liquid crystal display device,the color filter 34 is disposed in each of the regions which arepartitioned by the black matrix 32.

The counter-substrate CT may be configured to include a shield electrodefor reducing the influence of external electric field, and an overcoatlayer which is disposed with such a relatively large thickness as toreduce irregularities on the surface of the color filter layer 34.

When the counter-substrate CT and the above-described array substrate ARare disposed such that their first alignment film 20 and secondalignment film 36 are opposed, a predetermined gap is provided byspacers (not shown), which are disposed between both alignment films 20and 36. The liquid crystal layer LQ is composed of a liquid crystalcomposition including liquid crystal molecules, which is sealed in thegap between the first alignment film 20 of the array substrate AR andthe second alignment film 36 of the counter-substrate CT.

The liquid crystal molecules included in the liquid crystal layer LQ arealigned by restriction forces that are caused by the first alignmentfilm 20 and second alignment film 36. Specifically, at a time of noelectric field, that is, when there is no potential difference betweenthe potential of the pixel electrode EP and the potential of thecounter-electrode ET (i.e. when no electric field is generated betweenthe pixel electrode EP and the counter-electrode ET), the liquid crystalmolecules are aligned such that their major-axis direction is parallelto a rubbing direction S of the alignment film 20 and alignment film 36.The rubbing direction S, as shown in FIG. 3, is, for example, parallelto the column direction on the major surface of the array substrate AR.

The liquid crystal display device includes an optical element OD1 whichis provided on one of outer surfaces of the liquid crystal display panelLPN (i.e. that surface of the array substrate AR, which is opposite tothe surface thereof that is in contact with the liquid crystal layerLQ), and an optical element OD2 which is provided on the other outersurface of the liquid crystal display panel LPN (i.e. that surface ofthe counter-substrate CT, which is opposite to the surface thereof thatis in contact with the liquid crystal layer LQ). Each of the opticalelements OD1 and OD2 includes a polarizer plate, thereby realizing, forexample, a normally black mode in which the transmittance of the liquidcrystal panel LPN decreases to a minimum (i.e. a black screen isdisplayed) at the time of no electric field.

Further, the liquid crystal display device includes a backlight unit BLwhich is disposed on the array substrate AR side of the liquid crystaldisplay panel LPN.

In this liquid crystal display device, when a potential difference isproduced between the potential of the pixel electrode EP and thepotential of the counter-electrode ET (i.e. at a voltage applicationtime when a voltage of a potential that is different from the potentialof the counter-electrode ET is applied to the pixel electrode EP), atransverse electric field E1 is generated between the first majorelectrode portion EPa of the pixel electrode EP and the second majorelectrode portion ETa of the counter-electrode ET.

In this case, the distance D between the first major electrode portionEPa and the second major electrode portion ETa is set to be sufficientlygreat, compared to the gap G between the substrates. For example, thedistance D is about 10 μm or more (preferably 10 to 15 μm) and the gap Gis about 4 μm. Thus, a transverse electric field E1, which issubstantially parallel to the substrate major surface and issubstantially horizontal, is formed between the first major electrodeportion EPa and the second major electrode portion ETa. The distance D,in this context, is a distance between an edge of the first majorelectrode portion EPa on the second major electrode portion ETa side andan edge of the second major electrode portion ETa on the first majorelectrode portion EPa side. The gap G is a gap between the firstalignment film 20 and the second alignment film 36.

At this time, the liquid crystal molecule is driven such that itsmajor-axis direction is oriented from the rubbing direction S to adirection parallel to the transverse electric field E1. If themajor-axis direction of the liquid crystal molecule varies from therubbing direction S, the modulation ratio relating to the light passingthrough the liquid crystal layer LQ varies. Accordingly, backlight isselectively passed in accordance with the modulation ratio, and an imageis displayed.

The liquid crystal mode, which makes use of the transverse electricfield, is thus realized.

In the liquid crystal display device, the pixel electrode EP is formedon the array substrate AR, and the counter-electrode ET is formed on thecounter-substrate CT. Thus, the fabrication step of forming the pixelelectrode EP on the array substrate AR and the fabrication step offorming the counter-electrode ET on the counter-substrate CT can beperformed in parallel. In other words, this liquid crystal displaydevice can be formed by using a conventional process of avertical-electric-field mode liquid crystal display device, such as a TNmode liquid crystal display device. Therefore, there is no need toadditionally install or largely reassemble the manufacturing line, andan increase in manufacturing cost can be suppressed.

Further, in this liquid crystal display device, since thecounter-electrode ET is formed on the counter-substrate CT, it ispossible to dispose, as described above, the second major electrodeportion ETa, which is the counter-electrode ET, to be opposed to thesignal line X.

In the conventional structure in which the pixel electrode and thecounter-electrode are disposed on the same substrate, the pixelelectrode and the counter-electrode are, in many cases, disposed on theinside of neighboring signal lines X. In this case, the region betweenthe pixel electrode and the counter-electrode becomes an apertureportion which mainly contributes to display.

On the other hand, in the above-described structure in which the pixelelectrode EP and counter-electrode ET are disposed on the differentsubstrates, it is possible to dispose, in the pixel PX, the second majorelectrode portion ETa of the counter-electrode ET to be opposed to thesignal line X. In this case, the region between the signal line X andthe first major electrode portion EPa becomes an aperture portion. Inshort, compared to the conventional structure, the aperture portion canbe increased and the transmittance can be improved.

In addition, by disposing the second major electrode portion ETa to beopposed to the signal line X, it becomes possible to increase thedistance between the first major electrode portion EPa and the secondmajor electrode portion ETa, compared to the conventional structure, anda transverse electric field E1 in a direction, which is closer to thehorizontal direction, can be produced. Therefore, the transmittance canbe improved, compared to the conventional structure. Specifically, inthe present embodiment, the transmittance can be improved, compared tothe conventional structure, while the advantages of the conventionalstructure of, e.g. the IPS mode, such as low viewing angle dependencyand wide viewing angle characteristics, are maintained.

When misalignment occurs between the array substrate AR and thecounter-substrate CT, it is possible that a difference may occur indistance between the first major electrode portion EPa and the secondmajor electrode portions ETa on both sides which sandwich the firstmajor electrode portion EPa. However, since such misalignment occurscommonly to all pixels PX, the electric field distribution between thepixels PX does not vary, and the display of images is not affected.

By the way, as described above, the pixel electrode EP includes thefirst sub-electrode portion EPb in addition to the first major electrodeportion EPa. This first sub-electrode portion EPb is electricallyconnected to one end of the first major electrode portion EPa. The firstsub-electrode portion EPb, as shown in FIG. 3, is formed in atrapezoidal shape, and a short side of the two parallel sides isdisposed to be connected to the one end of the first major electrodeportion EPa. Two oblique sides, which connect the short side and longside, are line-symmetric with respect to the center line that isparallel to the column direction. In addition, the first sub-electrodeportion EPb is disposed equidistant from two signal lines X whichsandwich the first sub-electrode portion EPb.

FIG. 5 shows a first comparative example. In the first comparativeexample, too, the pixel electrode EP includes a first sub-electrodeportion EPb in addition to a first major electrode portion EPa. Thisfirst sub-electrode portion EPb is electrically connected to one end ofthe first major electrode portion EPa. In the first comparative example,the first sub-electrode portion EPb is formed in a rectangular shape,and the first sub-electrode portion EPb is disposed equidistant from twosignal lines X which sandwich the first sub-electrode portion EPb.

In the embodiment shown in FIG. 3 and in the first comparative example,at the time of voltage application, a transverse electric field E1 isgenerated between the first major electrode portion EPa and the secondmajor electrode portion ETa, and an electric field. E2 is generatedbetween the first sub-electrode portion EPb and the second majorelectrode portion ETa. Thus, the electric field E2 is generated inaddition to the transverse electric field E1 that is necessary for imagedisplay.

FIG. 6 shows a simulation result of an alignment direction of liquidcrystal molecules at a time of voltage application in the presentembodiment, and FIG. 7 shows a simulation result of an alignmentdirection of liquid crystal molecules at a time of voltage applicationin the first comparative example. In a region A and a region A′, theliquid crystal molecules are affected by the transverse electric fieldE1 that is generated between the first major electrode portion EPa andthe second major electrode portion ETa, and by the electric field E2that is generated between the first sub-electrode portion EPb and thesecond major electrode portion ETa, and the liquid crystal molecules arealigned in a direction different from the alignment direction for whitedisplay. Consequently, in the region A and region A′, the transmittanceis low and a dark line occurs. If such a dark line occurs in theaperture portion, the transmittance undesirably lowers.

According to the present embodiment, since the trapezoidal firstsub-electrode portion EPb is adopted, the interaction between thetransverse electric field E1 and electric field E2 is relaxed, and thedark line appearing in the aperture portion can be decreased. As shownin FIG. 6 and FIG. 7, the area of occurrence of the dark line is smallerin the region A than in the region A′. Hence, as in the presentembodiment, by forming the first sub-electrode portion EPb in thetrapezoidal shape, the transmittance can be improved. According to thesimulation that was conducted by the inventor, it was confirmed that thetransmittance in the present embodiment was increased by about 4%,compared to the first comparative example.

FIG. 8 shows a modification of the present embodiment. In themodification, the counter-electrode ET further includes a secondsub-electrode portion ETb. The second sub-electrode portion ETb isdisposed to be opposed to the first sub-electrode portion EPb so as toproduce a vertical electric field between the second sub-electrodeportion ETb and the first sub-electrode portion EPb. In particular, inthe example shown in FIG. 8, the second sub-electrode portion ETb isdisposed on the boundary side between the first major electrode portionEPa and the first sub-electrode portion EPb.

In addition, the second sub-electrode portion ETb is disposed in the rowdirection in a manner to cross the second major electrode portions ETa,and is electrically connected to the second major electrode portionsETa. In the illustrated example, the second major electrode portions ETaand the second sub-electrode portion ETb are integrally formed of thesame material.

According to the modification with this structure, at the time ofvoltage application, a vertical electric field E3 is formed between thefirst sub-electrode portion EPb and the second sub-electrode portionETb, in addition to the above-described transverse electric field E1 andelectric field E2.

FIG. 9 and FIG. 10 show simulation results of the relationship betweenan equipotential surface and an alignment direction of liquid crystalmolecules at a time of voltage application in the embodiment shown inFIG. 3 and the modification shown in FIG. 8.

As shown in FIG. 9, in a region B, a dark like occurs due to theinfluence of the transverse electric field E1 and electric field E2.

On the other hand, as shown in FIG. 10, in the modification, the liquidcrystal molecules are affected by the transverse electric field E1,electric field E2 and vertical electric field E3 in a region C. In theregion C, the transmittance is low, and a dark line occurs.

At this time, the region C is formed on a light-blocking portion by theinteraction between the electric field E2 and vertical electric fieldE3. Specifically, since the region B is formed in the aperture portion,the region B contributes to image display, and causes a decrease intransmittance. On the other hand, the region C is formed on the storagecapacitance line AY that is formed of the light-blocking material, anddoes not contribute to image display.

Specifically, since the dark line is shifted onto the light-blockingportion, the transmittance can be improved. It was confirmed that thetransmittance in the modification shown in FIG. 8 was increased by about7%, compared to the present embodiment shown in FIG. 6.

Next, in order to verify the advantageous effect of the modification, adescription is given of a second comparative example for comparison withthe modification. The second comparative example shown in FIG. 11 is aliquid crystal display device which is configured to operate in a liquidcrystal mode which uses a transverse electric field. This liquid crystaldisplay device includes a pixel electrode EP and a counter-electrode ETbetween a pair of signal lines X on the array substrate AR.

The transmittance was measured with respect to the modification shown inFIG. 8 and the second comparative example shown in FIG. 11. FIG. 12shows the result of measurement. When the transmittance in the secondcomparative example at the time of application of a maximum voltage(i.e. at the time of displaying a white screen) was set at 1.00, thetransmittance in the modification at the time of applying the samevoltage was 1.15.

As has been described above, according to the liquid crystal displaydevice of the present embodiment, the manufacturing cost can besuppressed, the viewing angle dependency is low, wide viewing anglecharacteristics are obtained, the transmittance can be improved, and animage with good display quality can be displayed.

Additional advantages and modifications will readily occur to thoseskilled in the art. Therefore, the invention in its broader aspects isnot limited to the specific details and representative embodiments shownand described herein. Accordingly, various modifications may be madewithout departing from the spirit or scope of the general inventiveconcept as defined by the appended claims and their equivalents.

In the example shown in FIG. 3, etc., in each pixel PX, the pixelelectrode EP includes a single first major electrode portion EPa, butthe pixel electrode EP may include a plurality of first major electrodeportions EPa. In an example shown in FIG. 13, in each pixel PX, thepixel electrode EP includes two first major electrode portion EPa. Inthis case, the second major electrode portion ETa is disposed betweentwo first major electrode portions EPa. Specifically, the first majorelectrode portions EPa and second major electrode portions ETa arealternately arranged in parallel in a combtooth pattern. In this case,the distance between each first major electrode portion EPa and eachsecond major electrode portion ETa is substantially equally set. In thisexample, too, the same advantageous effects as in the above-describedembodiment can be obtained.

The modification shown in FIG. 8 relates to the liquid crystal displaydevice using the trapezoidal first sub-electrode portion EPb. In thecase where the second sub-electrode portion ETb is disposed, the shapeof the storage capacitance portion is not particularly limited. Forexample, even with a liquid crystal display device using a rectangularfirst sub-electrode portion EPb, the same advantageous effects as in themodification can be obtained.

1-6. (canceled)
 7. A liquid crystal display device comprising: an arraysubstrate comprising a storage capacitance line extended in a rowdirection; and a pixel electrode which is disposed in each of pixels,the pixel electrode comprising: a first major electrode portion having astrip shape extended in a column direction; and a first subelectrodeportion which is positioned above the storage capacitance line and iselectrically connected to the first major electrode portion; acounter-substrate which is disposed to be opposed to the array substrateand comprises a counter-electrode which is common to the pixels, thecounter-electrode comprising second major electrode portions each havinga strip shape and a second sub-electrode portion; and a liquid crystallayer which is held between the array substrate and thecounter-substrate, wherein: the second major electrode portions aredisposed in parallel to the first major electrode portion in a mannerthat the first major electrode portion is interposed between the secondmajor electrode portions; and the second sub-electrode portion isopposed to the first sub electrode portion and is electrically connectedto the second major electrode portion.
 8. The liquid crystal displaydevice according to claim 7, wherein: the array substrate furthercomprises signal lines which are disposed along the column direction;and the first sub-electrode portion is disposed equidistant from twosignal lines which sandwich the first sub-electrode portion.
 9. Theliquid crystal display device according to claim 7, wherein the secondsubelectrode portion is disposed on the boundary side between the firstmajor electrode portion and the first sub-electrode portion.
 10. Theliquid crystal display device according to claim 7, wherein: the arraysubstrate further comprises a first alignment film covering the pixelelectrode; the counter-electrode further comprises a second alignmentfilm covering the counter-electrode; and a first rubbing direction ofthe first alignment film and a second rubbing direction of the secondalignment film are parallel to the column direction.
 11. A liquidcrystal display device comprising: an array substrate comprising astorage capacitance line extended in a row direction; and a pixelelectrode which is disposed in each of pixels, the pixel electrodecomprising: first major electrode portions each having a strip shapeextended in a column direction; and a first sub-electrode portion whichis positioned above the storage capacitance line and is electricallyconnected to the first major electrode portions; a counter-substratewhich is disposed to be opposed to the array substrate and comprises acounter-electrode which is common to a plurality of the pixels, thecounter-electrode comprising second major electrode portions each havinga strip shape and a second sub-electrode portion; and a liquid crystallayer which is held between the array substrate and thecounter-substrate, wherein the second major electrode portions aredisposed in parallel to the first major electrode portions in a mannerthat each of the first major electrode portions is interposed betweenthe second major electrode portions and that the first major electrodeportion and the second major electrode portion are alternately arranged,and the second sub-electrode portion is opposed to the first subelectrode portion and is electrically connected to the second majorelectrode portion.
 12. The liquid crystal display device according toclaim 11, wherein: the array substrate further comprises signal lineswhich are disposed along the column direction; and the firstsub-electrode portion is disposed equidistant from two signal lineswhich sandwich the first sub-electrode portion.
 13. The liquid crystaldisplay device according to claim 11, wherein the second subelectrodeportion is disposed on the boundary side between the first majorelectrode portions and the first sub-electrode portion.
 14. The liquidcrystal display device according to claim 11, wherein: the arraysubstrate further comprises a first alignment film covering the pixelelectrode; the counter-electrode further comprises a second alignmentfilm covering the counter-electrode; and a first rubbing direction ofthe first alignment film and a second rubbing direction of the secondalignment film are parallel to the column direction.
 15. A liquidcrystal display device comprising: an array substrate comprising a pixelelectrode which is disposed in each of pixels, the pixel electrodecomprising a first major electrode portion having a strip shape extendedin a column direction; and a rectangular first sub-electrode portionwhich is electrically connected to the first major electrode portion; acounter-substrate which is disposed to be opposed to the array substrateand comprises a counter-electrode which is common to a plurality of thepixels, the counter-electrode comprising second major electrode portionseach having a strip shape and a second sub-electrode portion; and aliquid crystal layer which is held between the array substrate and thecounter-substrate, wherein: the second major electrode portions aredisposed in parallel to the first major electrode portion in a mannerthat the first major electrode portion is interposed between the secondmajor electrode portions, and the second sub-electrode portion isopposed to the first sub electrode portion and is electrically connectedto the second major electrode portion.
 16. The liquid crystal displaydevice according to claim 15, wherein the array substrate furthercomprises signal lines which are disposed along the column direction;and the first sub-electrode portion is disposed equidistant from twosignal lines which sandwich the first sub-electrode portion.
 17. Theliquid crystal display device according to claim 15, wherein the secondsubelectrode portion is disposed on the boundary side between the firstmajor electrode portion and the first sub-electrode portion.
 18. Theliquid crystal display device according to claim 15, wherein: the arraysubstrate further comprises a first alignment film covering the pixelelectrode; the counter-electrode further comprises a second alignmentfilm covering the counter-electrode; and a first rubbing direction ofthe first alignment film and a second rubbing direction of the secondalignment film are parallel to the column direction.